body {
    margin: 0 auto;
    text-align: center;
}

/* 下层子节点居中且有缝隙 */
.child-center-has-gap {
    display: inline-block;
    padding: 10px 20px;
    border: #0ab169 2px solid;
    border-radius: 3px;
    margin: 2px 4px;
}

.child-center-has-gap > * {
    margin: 0 10px;
}

.child-center-has-gap div:first-child {
    height: 50px;
    border: #b1e3ca 2px solid;
    border-radius: 3px;
    margin-bottom: 5px;
    text-align: center;
    line-height: 50px;
}

.child-center-has-gap > pre {
    border: #b1e3ca 2px solid;
    border-radius: 3px;
    margin: 5px 2px;
    padding: 2px 4px;
    min-height: 50px;
}